She was arrested and placed in federal custody prior to being sent back to her native Ireland.

McCarthy denied she had anything to do with the 2013 death of Rehma Sabir, of Cambridge, and called the treatment she received by investigators "scandalous."

"They should be ashamed of themselves ... they just decided right away that I had killed the child," McCarthy told the Boston Herald. "That couldn't be further from the truth. I loved her and cared for her, 10 hours a day, five days a week."

On Monday, prosecutors dropped the charge after the medical examiner's office revised its original homicide ruling.

The office determined Rehma had a possibly undiagnosed condition that made her prone to bleeding and may have contributed to her death.

McCarthy had purchased a plane ticket to return to Ireland and hoped to voluntarily leave the country Tuesday evening.

But Neudauer stressed that McCarthy is a "significant violator" and will be formally deported, meaning she will likely face a minimum ban of 10 years before she can ever return to the U.S.

McCarthy's husband and some of her immediate family reside in the Boston area.

She entered the country in 2002 under a visa waiver program that only allowed her to stay 90 days. She doesn't have the right to a federal immigration hearing because she entered under the waiver program, Neudauer said.